In the prior art, the sport shoes are larger than necessary sizes so that the users feel comfortable. Referring to FIG. 1, a cross section view shows that a sport shoe is worn, in that D is a margin for providing an adjustable space to users. However the margin D will cause that the user feel inconvenient in exercise. Another defect occurring in this prior art is that the impact of the feet will apply upon the sole of the shoe so as to hurt the feet.